By Will Hawkins

Diets that work - The good, the bad and the science

We hear about new fad diets all the time - but what about the ones that have been around for years?

I've been delving into the science behind some of the world's most popular diets recently on my Instagram, and want to share my verdict with you to debunk some of the myths around:

Low-carb diets

'SIRT' diets (The Sirtfood Diet)

The 5:2 diet

Alkaline diets

Low-fat diets


Low-carb diets

  • Paleo diet
  • South Beach diet
  • Ketogenic diet
  • Atkins diet
  • Low-Carb High-Fat (LCHF) diet

How do low-carb diets work?

The principles of the diets mentioned above revolve around reducing your carbohydrate
intake and replacing it with varying proportions of proteins and fats, with LCHF and Ketogenic diets being the most excessive in terms of fat consumption.

Examples of what you can eat on a low-carb diet:

  • Meat
  • Vegetables
  • Fish
  • Eggs
  • Fruit
  • High-fat foods like cheese and butter

What can't you eat on a low-carb diet?

  • Pasta
  • Bread
  • Soft drinks
  • Ice cream
  • Processed foods
  • Cereals

Is going on a low-carb diet good for you?

Indeed, these diets have been reported in clinical studies to help improve markers of diabetes and also autoimmune diseases. One of the most exciting recent findings is that Ketogenic diets can help in treating childhood epilepsy and chronic pain.

However, for an otherwise healthy person, a lot of people can't maintain the diet as it's quite restrictive. When they return to eating carbohydrates there appears to be a trend towards regaining all the weight they had lost with potentially worse outcomes health-wise than before they began.

What's more, there is some evidence pointing towards high-protein intake being similarly harmful as high carbohydrate content (particularly for people with kidney disorders). Not to mention side effects such as constipation, halitosis, nausea and osteoporosis.

Ultimately, long-term evidence to advocate these diets is lacking. Essentially, it's a temporary fix. More research is needed to validate these low-carb diets that drastically remove beneficial carbohydrate sources, and the lack of different fruits, vegetables and fibre is something that would concern me.

My verdict:

For the reasons mentioned above, I can't condone low-carb lifestyles long-term, but I don't doubt that they could be beneficial and play an important role in clinical care.

The Sirtfood Diet

What is The Sirtfood Diet?

The Sirtfood Diet - or 'SIRT diet' - focuses on a small list of foods impacting a portion of our genetic pathways. 'SIRT' genes are what this diet is named after - increasing the activity of these genes is thought to reduce inflammation, control blood sugar and has been linked to reducing cancer risk.

The diet comes in two phases - the first phase is very restrictive when it comes to calories consumed, and the diet plan predominantly includes sirtfood juices. Phase two allows for three full meals a day - as long as they only contain the short list of sirtfoods allowed.

Examples of what you can eat on The Sirtfood Diet:

  • Apples
  • Parsley
  • Green tea
  • Dark chocolate
  • Kale
  • Blueberries

Is going on The Sirtfood Diet good for you?

While I welcome excitement about foods that have the potential to impact our genetic make-up, the SIRT diet focuses on a small list of foods impacting SOME genetic pathways, detracting from how complicated the human body really is.

The interaction between food and our genetics is a fascinating field. We have many layers of genetics in the body, and for every layer, certain foods are needed to maintain that layer.

I think this diet completely misses the point to be focusing on an exclusive group of ingredients, and doesn't encourage a healthy relationship with food. Every ingredient deserves a platform.

Indeed, apples, dark chocolate and green tea are examples that all increase SIRT gene expression, but they also contain a host of other micro-nutrients that are essential for processes in our body's cells. But as do legumes, broccoli, chilli and a whole bunch of other ingredients that don't fit the SIRT diet list.

My verdict:

The importance of a diet with a variety of ingredients is paramount. Don't limit yourself on what you can eat - there is some amazing foods to be tried out there! And don't get me started on 'juice cleanses', either

The 5:2 Diet

What is the 5:2 diet?

The 5:2 diet is based around the idea of intermittent fasting. For five days a week, dieters eat the recommended daily allowance (RDA) of calories, and how two days a week they eat just 25% of their RDA of calories.

The science used to formulate intermittent fasting diets like the 5:2 is really impressive. There appears to be numerous benefits of cyclical fasting. Though despite it's proposed benefits, the main question in reality is: can it be sustainable? and maybe even more importantly, enjoyable?

What can you eat on the 5:2 diet?

There are no restrictions on what you can eat during the 5:2 diet - it's entirely based on calorie consumption, rather than food groups.

However, clearly a bag of sugar compared to an equal calorie content of spinach is going to have drastically different effects on our body. Calorie counting does not account for this
difference so I'd suggest you exercise caution with this.

Is going on the 5:2 diet good for you?

I am convinced people have found benefits with this benefits from using this dietary
strategy, but I were to tell the majority of my clients I see to reduce their calories to 500 for
two whole days, I know exactly where they'd be telling me to go!

I don't count calories. For a lot of people, I find that it shifts the focus towards indiscriminate numbers on packets of food, and away from what actually is important: the quality and nutritional content of food we give to our body, as I mentioned earlier.

My verdict:

In terms of the concept of the diet, fasting, and the variations of fasting strategies, is an interesting area and warrants further research. Though what I think might be just as effective, and easier to incorporate into daily working life, is defined 'eating periods'.
Research has shown that the simple effort of eating at regular times within a 10-11 hour window can reduce your risk of diabetes and risk of heart disease. It stabilises insulin release and promotes a greater lipid oxidation (fat burning). If you're interested in a fasting strategy to allows you to maintain a healthy diet, this 'eating periods' is a logical and effective choice.

The alkaline diet

What is the alkaline diet?

The diet encourages people to consume foods that are more alkaline than acidic, in order to change the body's blood pH level (it's balance of acid-alkaline).

healthier foods, which isn't a bad thing! However, people deserve to be educated and told the truth about how food interacts with our biochemistry.

What can you eat on the alkaline diet?

The diet focuses on eating alkaline foods, aiming to consume only small amounts of acidic and neutral foods.

Alkaline foods include:

  • Leafy vegetables
  • Nuts
  • Broccoli
  • Avocado
  • Potatoes
  • Non-citrus fruits

Acidic foods include:

  • Many dairy products
  • Fish
  • Processed foods
  • Grains
  • Fruits like lemons, plums and grapes
  • Soda

Is going on the alkaline diet good for you?

Introducing 'alkaline' foods, such as vegetables and colourful fruit, is fantastic. But

rather than just focusing on 'alkalinity', we should look to focus on fibre and micro-nutrients, like magnesium.

Focusing on just 'alkalinity'; can potentially promote an obsessive and unnecessary way we view what we eat. I'm going to give you some insight as to why there is such a divide between nutritionists and the wellness industry here.

When non-medically trained, self-styled health 'gurus' are given a platform to influence people into believing they can change their blood pH with a diet high in alkaline foods, is not only incredibly frustrating, but a huge oversimplification of nutritional and physiological science.

My verdict:

I am an open-minded nutritionist, so perhaps one day we will learn more about 'alkalinity' but for now, the science does not support the claims.

Keep things simple: a great variety of fruit and vegetables, plenty of protein, and fluctuate carbs based on how active your day is.

The low-fat diet

What is the low-fat diet?

Reducing the fat content of our food intake and encouraging processed, low-fat options over the past few decades has probably been the most effective, yet destructive, health campaign of all time.

The diet is based on restricting your consumption of fats - particularly saturated fats - in order to improve cardiovascular health and, predominantly, lose weight.

Examples of what you can eat on a low-fat diet:

  • Plant-based foods
  • Beans and peas
  • Tofu
  • Low-fat yogurt and milk
  • Tuna

Is going on the low-fat diet good for you?

An over-indulgence in calories, particularly from fat, combined with apathy toward exercise was that generally accepted explanation as to why people were getting overweight or sick.

It's obvious, now, that this was not correct. 'Cholesterol-lowering' products and sugar-laden alternatives to fat that we used to promote are actually terrible options for the vulnerable cohort of people we're actually trying to help with this type of diet.

The recommendations for extreme restriction of saturated fat, cholesterol, and total fat are becoming obsolete, and latest research is proving fat not to be as detrimental as previously thought.

The morbid result of our fixation with replacing fats with refined and sugary carbohydrates is exemplified by our current lifestyle-related disease epidemic.

Take a good look at the Mediterranean diet, one of the largest and longest studied of eating habits, comprises three times more fat than 'fat-restricted' diets, and has shown impressive cardiovascular and diabetes protective effects.

My verdict:

My honest opinion is that we shouldn't fear fats, and that a 'good varied' proportion of high-quality fats are essential to health. I'll do a piece on each individual healthy fat, it's health benefits, and what foods to get them from.


What is the veganism?

The basis of veganism is to abstain from all animal products where possible, predominantly focusing on diet. The practice was actually started in the 1940s, with it only recently becoming a mainstream way of life.

What can't you eat as a vegan?

  • All meat (including fish)
  • All dairy products
  • Eggs
  • Products containing animal by-products (like gelatin)

Is going on a vegan diet good for you?

In recent times plant-based eating has become exceptionally popular. A number of documentaries have convinced many people of the supposed health benefits of veganism and the health risks of red meat.

They do have a lot of successes to feel smug about, that are well documented in literature. Lower rates of diabetes, cardiovascular disease, potentially even cancer It's compelling stuff,

I am a huge supporter of a diet that's largely made up of fruit and veg, but pure veganism doesn't come without its risks. B vitamins are noticeably lacking in vegans, as well as zinc, essential fatty acids and vitamin D.

Careful supplementation with extra nutrients is something I would advise to all 100% plant-based eaters that they should discuss with their health practitioner first. Also, it's important to remember that just because you go vegan, doesn't automatically turn you into a dementia-proof, cancer-kicking superhuman with spotless arteries.

If I lived on chips and pasta with tomato sauce I could feel pretty ethically minded about not having killed an animal for my dinner, but I probably wouldn't live for very long to tell people about it.

My verdict:

Ultimately, I endorse the idea of plant-based diets, whatever your reason for choosing to do so. However, educate yourselves within the dietary strategy of veganism before you choose to do so, in order to minimise potential risks

Wrapping up...

To summarise this series, what a lot of these diets have in common is a focus on weight loss as a positive outcome. But is this what we should be striving for?

Is weight management a reliable marker of general health and should this dictate how we judge the success of a diet? BMI is such a poor predictor of outcomes, yet many studies continue to use this as a standard.

Everyone has the ability to lose weight, tone up and feel lighter, but sometimes it's at the expense of health, rather than in pursuit of it.

I want you to feel 'well', and I'm convinced that good health, contrary to popular belief, is independent of size and especially weight. I think we could all do with a little less emphasis on weight as an outcome and focus more on wellbeing.

Your focus should be on health goals and habits, rather than physical endpoint this comes inevitably once you get the goals and habits right!

I want to encourage you to think along the lines off adding as much nutrient-dense foods to your diet as possible. We have the opportunity to be truly nourished, rather than skip from diet to diet in the hope we hit the 'carb-protein-fat' ratio and achieve that infamous 'perfect weight'.

The foundation of your health, starts on your plate. As always, I will be doing the best I can to guide you in the right direction.